Computer animation systems and methods are well known in the art, serving a wide range of applications in which a computer is used to generate and/or manipulate moving images. In recent years, the rapid advance in computing speed and reduction in cost of personal computers (PC's) has made computer animation widely accessible. Because of the relatively heavy computation load associated with three-dimensional (3D) image rendering, most of the animation programs for PC's have been able to offer only 2D imaging or very limited 3D effects. Similarly, although 2D animations are now commonly conveyed from one computer to another over the Internet and other network systems, the bandwidth limitations of the Internet have, at least until recently, made it generally impractical to convey 3D animations.
Software tools and languages are available to assist programmers in creating 3D animations. For example, "LightWave 5.0," produced by Newtek, Inc., of Topeka, Kans., is a software package that enables users to define and manipulate geometrical models and animations of 3D graphic objects within a computer animation environment. Such objects are defined as skeletons, or hierarchies of geometrical shapes that are connected together at joints. These objects may further include methods, or program routines, that define the basic movements of the joints. Thus, an animated humanoid character may be defined by a skeleton including torso, head, arms, legs, hands, feet, and other features, with interlinking joints and methods that describe walking, running, hand-waving and other actions. Motion of the character along a desired path in a 3D virtual space may be engendered by indicating positions of the object in two or more key frames, whereupon the intermediate positions of the object between the key frames are interpolated, using the appropriate methods belonging to the object.
Based on the 3D geometrical definition of the object, an image of the animated character is rendered on a computer screen. Various software packages are available for 3D rendering, for example, "RenderWare V2.0," produced by Criterion Software Ltd. of Surrey, UK. The rendering software typically takes into account the effects of light, shade, color, surface textures, perspective and other visual elements, to create a convincingly "3D" image on the flat computer screen. Generally, multiple 3D objects are rendered together, along with a suitable background, to form a single image on screen.
U.S. Pat. No. 5,261,041, to Susman, which is incorporated herein by reference, describes a computer-controlled animation system based on manipulation of animated objects. Each object includes state data and methods, or functions, defining the behavior of the object. The objects also have associated affect volumes and affect agents, or methods, that determine how they will interact with each other as an animation sequence progresses. The animation sequence is governed by a set of rules, graphs or scripts. The behavior of the objects in the sequence is modeled and rendered on a display screen.
U.S. Pat. No. 5,483,630, to Unuma et al., which is incorporated herein by reference, describes a method for representing motion of multiple-jointed objects, for use in computer animation. The bending angles of the joints of a multiple-jointed object are represented by functions expressed independently of the length between the joints. Based on the functions, contour data are produced representing the motion of the joints, which data are used in rendering the objects in computer animation sequences. Parameters of the functions can be adjusted so that the motion of the joints has a desired character, for example, running or walking motion, or motion having a manner intended to give a sense of an emotional quality.
U.S. Pat. No. 5,267,154, to Takeuchi et al., which is incorporated herein by reference, describes a system for producing "biological images," i.e., animated computer images of human and animal characters. Images are synthesized by combining data from several databases in which shapes, motions and external features and textures are stored. The system is used to produce a variety of 3D animated characters, which take part in computer-animated image sequences.
U.S. Pat. No. 5,577,185, to Tunnell et al., which is incorporated herein by reference, describes a method and apparatus for creating computer-animated puzzles. The puzzles are made up of animated objects, such as structural members and characters, displayed on a computer screen. Each of the objects has a set of programmed physical and behavioral attributes, as a result of which the objects appear on screen to be aware of and to react to one another. They are programmed to appear to obey physical laws, such as the laws of gravity and motion, and to exhibit natural tendencies, such as hunger and affinity. The puzzles are created by selecting the desired objects from a menu displayed on the computer screen.
Computer-animated images may be overlaid on other images and/or windows on a computer display screen. For example, U.S. Pat. No. 5,546,518, to Blossom et al., which is incorporated herein by reference, describes a system and method for composing a display frame of multiple, layered graphic "sprites." A sprite is a graphic image that forms a part or a region of an overall computer display screen. The sprites are overlaid one above the other. The sprites preferably include transparent pixels in certain areas, through which underlying graphics can be seen. The system of sprites is used to combine video and/or animated images together with still images on a single screen.
Recently, tools have begun to emerge for sending and receiving 3D animations over computer networks, such as the Internet, for example, Version 2.0 of the Virtual Reality Modeling Language (VRML 2.0), as described in "Moving Worlds," at http://vrml.sgi.com (Silicon Graphics Inc.), and incorporated herein by reference. VRML 2.0 was developed by a group of companies to provide a language for creating animations in a compact form that is convenient for transmission over the Internet, and for viewing the animations at the receiving end. VRML 2.0 includes conventions for a user at a source computer to define and organize elements of an interactive animated image, such as 3D object geometries, surface textures, motion and action scripts and to encapsulate these elements for Internet transmission. When the encapsulated elements are received by a target computer having VRML-compatible network browser software, the animated image created at the source computer is rendered on the target computer screen.
Viewers of 3D animations generally require user interface software to enable them to observe and manipulate the animated images. Such software is known in the art, for example, "CosmoPlayer," a VRML 2.0-compatible network browser, available from Silicon Graphics at http://vrml.sgi.com, as described above. CosmoPlayer operates as a "plug-in" to an Internet web browser, such as Netscape "Navigator" or Microsoft Internet Explorer." CosmoPlayer enables a user to view animations of 3D objects and to vary a point of view from which the animations are rendered to the user's computer screen by means of "free navigation" in a virtual 3D space. It will be appreciated that because the computer screen and user controls are essentially two-dimensional, "free navigation" is generally difficult for a non-expert user to master.
Computer-animated images may likewise be used to create an animated electronic meeting place, as described, for example, in U.S. Pat. No. 5,347,306, to Nitta, which is incorporated herein by reference. Each participant in a meeting has a terminal with prestored local animation graphics. The terminals are connected to a network, over which the meeting takes place. The meeting is shown on the display of each of the terminals using real-time animated 3D graphic characters and sound, representing the participants' motions, expressions and speech. Each of the participants is represented in the animation by one of the animated characters, having a persona which may be chosen by the participant. The characters in the animated meeting are driven by sensors that sense the movement and speech of the actual participants. The participants may also use view controls, such as a joystick, to zoom or to alter their viewing perspectives.